Customer-owned equipment enablement, please?

I upgraded to a 2 gig plan (part of a bulk account with my complex), but I'm being forced to upgrade to a different model gateway. Unfortunately, the only gateway that will actually work for my needs (bridge mode-capable, 2+ multi-gig ports) is the XB10 that I strongly suspect they won't give me. I have all the hardware I need to run my own network directly off of the ONU, but support has NO idea what I'm talking about and tells me its not supported, which I know is completely false. Just disable MACsec on my ONU and let me use my equipment!